I wouldn't be surprised if he thought you were brushing him off. I've had it happen where I've run into college friends who don't recognize me at first, but not anyone who flirted with me. I know what you mean by strange, affirming experiences though.
I've been recalling transition-related experiences recently because I recently disclosed to my bf and we've been talking about my transition a lot, and so I end up talking about it to other people. I was telling my sister the other day that about a year after my operation, I went to a friend's art opening with a male friend and ended up meeting two other guys there. Afterwards I was planning to go to North Beach where another friend had a bonfire, and they all decided to join me.
So I ended up walking to the beach with three guys, and we had a bit of trouble locating my friend, and the three of them started arguing amongst themselves about directions, etc. That was when it dawned on me that they were all probably interested in me, which ended up being true (I dated one of them for the next year or so). There was definitely something both bizarre and satisfying, after having gone through all the turmoil of transition, that I was suddenly someone to be fought over.